Prognostic Value of Measurable Residual Disease in Patients with AML Undergoing HSCT: A Multicenter Study

SIMPLE SUMMARY: In patients diagnosed with acute myeloid leukemia (AML), relapse remains the main cause of mortality after allogeneic hematopoietic stem cell transplantation (HSCT). The detection of measurable residual disease (MRD) by multiparameter flow cytometry in AML patients undergoing HSCT is a powerful predictor of outcome. The aim of this study was performed a retrospective multicenter study to evaluate the prognostic value of MRD by second generation of MFC among patients undergoing HSCT, using recommendations from the Euroflow consortium. MRD levels prior to transplantation significantly influenced outcomes irrespective of the conditioning regimen. Positive MRD on day +100 after transplantation was associated with an extremely poor prognosis. Detection of positive MRD prior to and after transplantation performed with standardized technical conditions has prognostic value in real life. ABSTRACT: Allogeneic hematopoietic stem cell transplantation (HSCT) represents the best therapeutic option for many patients with acute myeloid leukemia (AML). However, relapse remains the main cause of mortality after transplantation. The detection of measurable residual disease (MRD) by multiparameter flow cytometry (MFC) in AML, before and after HSCT, has been described as a powerful predictor of outcome. Nevertheless, multicenter and standardized studies are lacking. A retrospective analysis was performed, including 295 AML patients undergoing HSCT in 4 centers that worked according to recommendations from the Euroflow consortium. Among patients in complete remission (CR), MRD levels prior to transplantation significantly influenced outcomes, with overall (OS) and leukemia free survival (LFS) at 2 years of 76.7% and 67.6% for MRD-negative patients, 68.5% and 49.7% for MRD-low patients (MRD < 0.1), and 50.5% and 36.6% for MRD-high patients (MRD ≥ 0.1) (p < 0.001), respectively. MRD level did influence the outcome, irrespective of the conditioning regimen. In our patient cohort, positive MRD on day +100 after transplantation was associated with an extremely poor prognosis, with a cumulative incidence of relapse of 93.3%. In conclusion, our multicenter study confirms the prognostic value of MRD performed in accordance with standardized recommendations.